A Tennessee man has plead guilty to charges that he killed his mother- and father-in-law with a package bomb, and prosecutors said he killed the couple because he owed them tens of thousands of dollars. Richard Parker will have to serve life in prison without parole. Parker is the son-in-law of Jon and Marion Setzer, who were killed after a package bomb exploded at their house in February. The Setzer’s are formerly from Johnson City. Prosecutors also revealed a motive in the deaths, saying Parker owed the Setzers about $40,000.